Battle of the Brains - Grade 9 Science Quarter 1-4 Quiz

What is the smallest unit of matter?

• Element

• Atom

• Molecule

• Compound

Answer explanation

The smallest unit of matter is the atom, which consists of protons, neutrons, and electrons. Elements are made up of atoms, while molecules and compounds are formed from two or more atoms bonded together.

Which subatomic particle carries a negative charge?

• Proton

• Neutron

• Electron

• Nucleus

Answer explanation

The electron is the subatomic particle that carries a negative charge, while protons carry a positive charge and neutrons are neutral. The nucleus is made up of protons and neutrons, but does not carry a charge itself.

Which of the following is an example of a homogeneous mixture?

• Oil and water

• Saltwater

• Sand and gravel

• Vinegar and soy sauce

Answer explanation

Saltwater is a homogeneous mixture because the salt dissolves completely in water, creating a uniform solution. In contrast, oil and water, sand and gravel, and vinegar and soy sauce are heterogeneous mixtures.

What is the law of conservation of mass?

• Mass is created during a reaction

• Mass is destroyed during a reaction

• Mass remains constant in a chemical reaction

• Mass changes based on temperature

Answer explanation

The law of conservation of mass states that mass remains constant in a chemical reaction, meaning that the total mass of reactants equals the total mass of products. Therefore, mass is neither created nor destroyed.

What is the acceleration due to gravity on Earth?

• 9.8 m/s²

• 8.9 m/s²

• 10.8 m/s²

• 12.2 m/s²

Answer explanation

The acceleration due to gravity on Earth is approximately 9.8 m/s². This value is widely accepted and used in physics to describe the force of gravity acting on objects near the Earth's surface.

Which Newton’s Law states that "An object at rest stays at rest unless acted upon by an external force"?

• First Law

• Second Law

• Third Law

• Law of Universal Gravitation

Answer explanation

The statement "An object at rest stays at rest unless acted upon by an external force" describes Newton's First Law of Motion, which emphasizes the concept of inertia.

Which of the following materials is a good conductor of electricity?

• Rubber

• Copper

• Plastic

• Glass

Answer explanation

Copper is a metal known for its excellent electrical conductivity, making it a good conductor of electricity. In contrast, rubber, plastic, and glass are insulators and do not conduct electricity well.

What is the product when an acid reacts with a base?

• Water and carbon dioxide

• Salt and water

• Oxygen and hydrogen

• Hydrogen gas

Answer explanation

When an acid reacts with a base, the products are salt and water, a process known as neutralization. This is why 'Salt and water' is the correct answer.

What part of the electromagnetic spectrum is used in X-ray imaging?

• Infrared

• Radio waves

• X-rays

• Microwaves

Answer explanation

X-ray imaging specifically utilizes X-rays, which are a form of electromagnetic radiation. This makes 'X-rays' the correct choice, as the other options (infrared, radio waves, microwaves) are not used in this type of imaging.

What is the most abundant gas in Earth’s atmosphere?

• Oxygen

• Nitrogen

• Carbon dioxide

• Helium

Answer explanation

Nitrogen is the most abundant gas in Earth's atmosphere, making up about 78% of it. In contrast, oxygen comprises about 21%, while carbon dioxide and helium are present in much smaller amounts.